| Value | Category | Cases | |
|---|---|---|---|
| -9 | Don't know (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| -7 | Never regiestered (spontaneous) | 0 | 
                                    
                                    0%
                                 | 
| 1993 | 1 | 
                                    
                                    0.3%
                                 | |
| 1995 | 3 | 
                                    
                                    1%
                                 | |
| 1996 | 2 | 
                                    
                                    0.6%
                                 | |
| 1997 | 3 | 
                                    
                                    1%
                                 | |
| 1998 | 5 | 
                                    
                                    1.6%
                                 | |
| 1999 | 4 | 
                                    
                                    1.3%
                                 | |
| 2000 | 3 | 
                                    
                                    1%
                                 | |
| 2001 | 3 | 
                                    
                                    1%
                                 | |
| 2002 | 2 | 
                                    
                                    0.6%
                                 | |
| 2003 | 3 | 
                                    
                                    1%
                                 | |
| 2004 | 3 | 
                                    
                                    1%
                                 | |
| 2005 | 3 | 
                                    
                                    1%
                                 | |
| 2006 | 4 | 
                                    
                                    1.3%
                                 | |
| 2007 | 4 | 
                                    
                                    1.3%
                                 | |
| 2008 | 13 | 
                                    
                                    4.2%
                                 | |
| 2009 | 7 | 
                                    
                                    2.3%
                                 | |
| 2010 | 23 | 
                                    
                                    7.4%
                                 | |
| 2011 | 13 | 
                                    
                                    4.2%
                                 | |
| 2012 | 23 | 
                                    
                                    7.4%
                                 | |
| 2013 | 17 | 
                                    
                                    5.5%
                                 | |
| 2014 | 21 | 
                                    
                                    6.8%
                                 | |
| 2015 | 21 | 
                                    
                                    6.8%
                                 | |
| 2016 | 16 | 
                                    
                                    5.1%
                                 | |
| 2017 | 23 | 
                                    
                                    7.4%
                                 | |
| 2018 | 28 | 
                                    
                                    9%
                                 | |
| 2019 | 24 | 
                                    
                                    7.7%
                                 | |
| 2020 | 16 | 
                                    
                                    5.1%
                                 | |
| 2021 | 18 | 
                                    
                                    5.8%
                                 | |
| 2022 | 5 | 
                                    
                                    1.6%
                                 |